Parking brake question

Discussion in 'Gen 5 Prius Technical Discussion' started by HamiltonPrius, Nov 29, 2025 at 11:03 AM.

  1. HamiltonPrius

    HamiltonPrius Member

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    What is the purpose of the parking brake button? When you put the car in park it automatically engages the parking brake. When you put the car in drive the parking brake automatically disengages.

    I’m trying to think of a use for the parking brake button…..I can’t. What am I missing?
     
  2. KMO

    KMO Senior Member

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    The automatic parking brake can be disabled, in which case it is the manual control.

    And I suspect manual control is a legal requirement.
     
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  3. ColoradoBoo

    ColoradoBoo Senior Member

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    Yes I think if you hold it down for 3-5 seconds it will turn off the automatic feature.

    Another puzzling thing, in my wife's 2024 Corolla Hybrid is the "Hold" button....I know it's for use like when you're at a stop light and don't want to hold down the brake pedal (or in a drive through) BUT why does Toyota put TWO "HOLD" symbols on the dash?? That's puzzling
     
  4. HamiltonPrius

    HamiltonPrius Member

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    Is there a setting that can turn off the auto parking brake? But if you mean the auto parking brake can be turned off by clicking the parking brake that’s true but why would anyone do that?
     
  5. HamiltonPrius

    HamiltonPrius Member

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    So what you are saying is if I put the car in park and the auto parking brakes engages I can hold the parking brake down for 3-5 seconds and the next time in put the car in park the auto parking brake will not engage?
     
  6. ColoradoBoo

    ColoradoBoo Senior Member

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    Yes...did you try it? It's 17 degrees this morning so I'm not going out to try it in my wife's car! (Or get her Owner's Manual to look it up!)
     
  7. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Before I raise the front of any car, I like to tap heavy, rubber wheel chocks fore and aft of each rear wheel, and then release the parking brake. That way, when the front goes up, the rear axle is free to hinge, but pinned, not fighting the parking brake. One time for having the parking brake off.

    I dislike those electronic parking brakes, find them a PITA, both setting and releasing. Seems like they're a convenience for manufacturers, not so much for anyone else. Definitely complicates rear brake jobs too.
     
  8. VelvetFoot

    VelvetFoot Active Member

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    The manual also mentions cold weather operation. I have it set to Auto and probably will keep it that way over the winter. I live for thrills.
     
  9. Hammersmith

    Hammersmith Senior Member

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    I had an interesting morning. I'm not sure if the automatic parking brake was a symptom or a cause.

    Because of bad weather, my car has been mostly sitting for the last week. A few short trips in between for groceries and the like. The temps have also dropped from the 40s-50s down to the 10s-20s this week. I went to fill up the car this morning and it started fine. Drove to the station(1.3mi) and popped the fuel door. Car gave a single long beep while I was at the pump, but I ignored it in the moment. Filled, closed it up, and went in to pay.

    Came back out, got in, and the car was in Power On mode, not Ready. Tried to start it, and it said EPB Activation Stopped Incompletely, as well as other errors. I tried manually cycling the parking brake, but it didn't work and I eventually got a low battery message and then later a lot of flashing lights(which usually confirms a low 12V batt). I eventually got a jump and the car worked properly from then on(drove it 100mi round trip at highway speeds so the batt should be recharged - I'll probably throw a tender on for awhile to be certain).


    So the question is whether the EPB malfunctioned due to the cold and drained the 12V battery while attempting and failing to actuate because it froze up, or whether the battery was barely hanging on and the EPB activation when I stopped for fuel was just enough to put it over the edge so it couldn't restart? It's a pretty new battery(maybe 8 or 9 months old), but the EPB has also handled over two winters by this point(one of them very, very cold) without having any problems. Neither seems to be the smoking gun.

    The coincidental thing is that I'm convinced my old NoCo 1000A jump pack is mostly toast, so it's out of the car while I wait for my new Gooloo 4000A jump pack with preheating tech to get here this coming week. So the one time I needed a jump pack is the one time I didn't have one. lol
     
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  10. schja01

    schja01 Senior Member

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    My door locks are tied to the parking brake. I think that's the default from the factory.
    If I "park" the doors unlock. I find the large "P" button easier to use to unlock the doors.
     
  11. RRxing

    RRxing Senior Member

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    The explanation in the Owner's Manual.
     
  12. HamiltonPrius

    HamiltonPrius Member

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    Didn’t work for me. It only disengaged the parking that the one time.
     
  13. Gokhan

    Gokhan Senior Member

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    No, it is not your electronic parking brake. It is your battery. Was it you who was torturing his battery so that it could fail and he could get a free replacement under warranty? I don’t remember.

    I highly recommend the Uplus AGM battery sold on Amazon I have a dedicated thread on. I also highly recommend connecting a Noco Genius every few months to fully charge the battery, as the car will never fully charge the battery otherwise due to its buggy BMS. You might want to do it more frequently if you don’t drive much. Since you had a full drain, your battery has degraded and you might want to consider replacing it.
     
  14. VelvetFoot

    VelvetFoot Active Member

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    upload_2025-11-30_7-3-59.png
     
  15. Xse

    Xse Member

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    My epb has been off when parked in my garage so the brakes don’t bind
    I manually on and off the epb myself like regular handbrake when I go places
    If you decide to take it off and manual activate yourself
    Simple hold epb for a few seconds info will appear on the screen
    Voila
     
  16. VelvetFoot

    VelvetFoot Active Member

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    I might turn it off for the winter.
     
  17. Mendel Leisk

    Mendel Leisk MMX GEN III

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    We’re around 3k kms a year, on our ‘10: it LIVES on a smart charger regimen, near-constantly.
     
  18. Xse

    Xse Member

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    Both my Miata/Prime also live on a battery plus tender since 94
    Again plugged in daily
    The Prius’s battery CCA is (a joke)as low as my Miata which is in hibernation right now
    They may have over engineered the Prius forgetting the 12 Volt battery

    if you live on a fairly level ground I would deactivate it (bind, seize who knows)
    On a hill make sure it’s activated or your car might disappear
     
  19. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Lowish CCA can improve the amp hours; the latter is important as well, I believe higher numbers improve the battery's ability to bounce back from a drain?
     
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